What are the pros and cons of removing the Catalytic Converter? My truck is exempt from emissions and it wouldn't surprise me if it has the original cat...in a couple of months i plan on putting some type of performance muffler maybe a flowmaster or thrush glasspack

I've used a flowmaster 50 series delta flow on a 3.8 v6 and it didn't have too bad of a sound for a 6...I'm wondering what muffler sounds good on the slant. I like a low deep mellow sound myself...if i remove the cat will it make any muffler that i put on it even louder than what it would be with the cat?

I have a glasspack and am happy. At idle it is pretty quite but give it some gas and she rumbles pretty good. I also pointed my tail pipe down so it will bounce back up a bit.

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2006 Jeep Commander
2013 Chrysler 200

1964 Valiant 4 Door
1965 Plymouth Barracuda
1967 Chevy Camaro

I have a flowmaster 40, and love the sound. It's on the louder side, if that's fine for you.

https://www.youtube.com/watch?v=jZwD1o8BCvQ

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69 Plymouth Valiant

Being mine was original and pretty well shot, I deleted it. Now the replacement pipe was autozone special for an 81 d150 which gets you all the way to pointing toward the rear on the passenger side. Everyone here pretty much recommends 2.25" and I know the autozone pc isn't but I didn't know at the time. Deleting my cat help it breath a bit since it was less restrictive and opened up some room in the engine bay. (Pics in build thread) I went w an autozone "thrush welded" nice and mellow idle and cruising, give it gas and it has a meaner note but no cracks and pops and not overly angry. I prefer go and not show but that's me.

Now, questions. Pros would be less restriction and one less part to buy
Cons- federal law says can't do it, just read that in another post (reed posted I think) chances being caught slim to none. And little less healthy for earth.
As far as making a muffler sound louder, I wouldn't know, one would think since there's less to muffle it (straight through)
Pohlman

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225, Offenhauser, Holley 350, A833OD, 3:55, GM HEI,99 Durango starter
BOOSTED! WH1C, BIG FMIC, 10#
Operation Noble Eagle 03-05
Operation Iraqi Freedom 05-07
Operation Enduring Freedom 12- 13

Otateral,

Nice vid your plymouth sounds awesome! Looks like you've done a great job bringing it back to life...I felt like you would be able to get a nice exhaust tone out of the slant (especially for a 6 cylinder). Do you have to have your car emissions tested in Cali?

Thanks for the input guys i'll have to think about how i want to handle it but it sounds like going with flowmaster or glasspack either way will be fine...

Ssg,

My truck still has the catalyst that connects to the exhaust manifold in the engine bay. Eventually i will take that out as well...it looks like where the main pipe connects to the catalytic converter the pipe size there is 2 1/2" from what i can tell and after the cat it reduces to 2". I'll have to decide if i want to roll with 2 1/2, 2 1/4, or 2 inch

I want to remove the cat to make sure it's not clogged up and causing some restriction and later on if i ever needed to have emission testing i would need to put a new cat on anyway...

I changed the differential fluid and put on a new chrome plated cover that has a threaded check plug (Spectre 6093) for the chrysler 10 bolt cover...It only cost $26.00 from autozone and comes with a gasket and chrome plated bolts i will post pics in the Transmission & Rearend later
i don't know if you've done this to your truck yet but i wanted to get away from the rubber check plug and at that price i think it's a great deal

It fits '61-'89 Chrysler cars & trucks with 8-1/4" ring gear

Here's a link

http://www.autozone.com/autozone/parts/ ... 810_19153_

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1984' Dodge D150 Utiline Bed
Slant 6 225, Holley 1920 Carb
A833 4 Speed O/D Transmission

Thanks. Mine is smog exempt because of its age. If you have to get it smogged every 2 years, I would be really wary of what you do to the exhaust.

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69 Plymouth Valiant

kxracer728,

I have tried several muffler brands. The deepest sound you will get is from a 2.5" FM 70 because of its size. I happen to like deep and quiet so I put on a 2.5" FM HP2 in front of it. The FM 40 sounds good at an idle but very raspy in the higher RPM. The FM70 sounds like a FM40 at idle but maintains that smooth mellow sound all the way up in RPM with out the peaky rasp.

Click on the red link below to view pictures of the set up. Got to slide show mode for bigger photos.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Otateral,

My truck is emissions exempt...here in arizona if a car or truck is older than 25 years and you have collector car insurance your exempt from emissions other than that the car or truck has to be 1966 model or older.

What is the year range in Cali?

Aggressive Ted,

Your 74' Dart looks REALLY NICE ! I bet that thing runs like a champ...the intake and holley 1920 carb i'm using on my truck right now came off a 72' dart swinger...

Here is a cool vid of a Chevelle 540 Flowmaster 70 series mufflers on youtube. It's worth checking out

http://www.youtube.com/watch?v=d1GXIamYeJk

Here's another vid of Flowmaster Muffler Comparison

http://www.youtube.com/watch?v=YlGqSd7QjWQ

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1984' Dodge D150 Utiline Bed
Slant 6 225, Holley 1920 Carb
A833 4 Speed O/D Transmission

Thanks! Yes it runs very well.

Great links to the muffler tests. Wish I new about that before I did my own tests....kind of expensive the way I learned. I bought several mufflers and ran them one at a time and in different configurations and different combinations since they act differently on a SL6. Started at 2" diameter and ended up at 2.5" diameter. A Flow Master Hush Power 2 in the front and a Flow Master 70 in the back.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Yeah, that's definately an expensive way to learn...but with mufflers you don't know how it's going to sound on your vehicle until you put it on.

I think flowmaster did a good thing with the delta flow technology it really does help reduce the interior sound...

Here is another link to a pretty mean sounding slant 6 being started after winter storage

http://www.youtube.com/watch?v=LBHdiZRl6Tk

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1984' Dodge D150 Utiline Bed
Slant 6 225, Holley 1920 Carb
A833 4 Speed O/D Transmission

Ok,

Just letting everyone know that i'm going to try one of the magnaflow glasspacks the 2 1/2" model 18146 it cost 39.99 at pepboys. I picked one up today they usually keep them in stock so i didn't have to order it

I'm going to disconnect the exhaust where it meets with the cat and set the muffler up from that point...i want to see if the cat is plugged up and causing some of the performance problems that i'm having

It might take me a week or so to work it out but i'll post results afterward

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1984' Dodge D150 Utiline Bed
Slant 6 225, Holley 1920 Carb
A833 4 Speed O/D Transmission

I took the cat off yesterday and this is what came out of it...



I will have to see how much this helps some of the performance problems i was having...

Right now i'm just going to bolt the glasspack on where the cat was at...but i'm wondering if i will have a problem with getting enough back pressure? I know if the exhaust system doesn't get enough back pressure you will loose HP and fuel economy

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1984' Dodge D150 Utiline Bed
Slant 6 225, Holley 1920 Carb
A833 4 Speed O/D Transmission

that looks like the cat that is under the passenger side? The one that may have been there on my 84 was not there so cant help there. The one on mine was located in the engine bay about 4' below the connection to the exhaust/intake manifold. It wasnt as bad as yours but was still slowing things down. it can be seen here. http://imageshack.us/a/img90/8479/engineoriginal.jpg
Not too sure about the back pressure as most on here seem to like the free flowing and some of the members with 20+ mpg I believe have 2.25' or larger free flow. so no worries there. keep at it and us posted. always good to see updates.
Pohlman

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225, Offenhauser, Holley 350, A833OD, 3:55, GM HEI,99 Durango starter
BOOSTED! WH1C, BIG FMIC, 10#
Operation Noble Eagle 03-05
Operation Iraqi Freedom 05-07
Operation Enduring Freedom 12- 13

kxracer728,

You could install a 12" Flow Master HP2 in it's place to provide the correct balance......

I am using a the 18" version. You can look at the pics by clicking on the red link below my name. Running 2.25" head pipe on back to 2.5" all the way back.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

OK, fellow slant sixers...i finally made a break thru! I've been working on this truck since November 2012 and spent hundreds of dollars and countless hours working and trying to tune this truck and the biggest problem this truck had was a restricted CAT (Are you Kidding ME)!

After removing the cat and the rest of the exhaust system from the cat back I temporarily mounted the new magnaflow glasspack and took a test drive...

Ssg, I NOW have a TRUCK!!! This thing runs so much better and i feel like i can move and drive now...I'm in a state of "Euphoria". I know what a slant 6 can actually do now. It still needs some tuning but i'm ready roll and spin some tires

Here are some pics of the temporary exhaust setup...







Ssg,

Removing the front cat is the next step to make sure it's not causing some kind of restriction because i know that it is the original catalyst as well...i know that you can buy the front main pipe from orielly's for 14.99 but how did you go about getting it to mount up to the exhaust flange on the main exhaust manifold?

Aggressive Ted,

I'll have to figure out how i want the exhaust to be more permanent...right now it's not that loud but the exhaust tone isn't as good as i would like. I'll have to see how that changes after removing the front catalyst and making sure it's not causing some restriction

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1984' Dodge D150 Utiline Bed
Slant 6 225, Holley 1920 Carb
A833 4 Speed O/D Transmission